Properly managing nitrogen for high-yield rice varieties is important for getting the most out of them. In this study, researchers looked at how different levels of nitrogen affected the growth and yield of two rice varieties, BRRI dhan58 and BRRI dhan75, in different growing seasons. They found that BRRI dhan58 responded better to nitrogen in the dry season, while BRRI dhan75 did better in the wet season. The best amount of nitrogen for BRRI dhan58 was 142 kg/ha, and for BRRI dhan75 it was 82 kg/ha. The efficiency of nitrogen use was higher for BRRI dhan58 in the dry season, but decreased with higher nitrogen levels in both seasons. This shows that using the right amount of nitrogen for each variety in the right season is key to getting the most rice without wasting fertilizer.